A social service agency plans to conduct a survey to determine the mean income of its clients. The director of the agency prefers that you measure the mean income very accurately, to within + or - $500 from a sample taken 2 years ago, you estimate that the standard deviation of income for this population is about $5000 your job
1. The amounts (in ounces) of juice in eight randomly selected juice bottles are: 15.4 15.7 15.2 15.8 15.8 15.4 15.0 15.6 Assuming the population of amounts in juice bottles is known to be normally distributed, create a 95% confidence interval estimate for , the mean amount of juice in all bottles. You will b
Q1: Why does the sample size play such an important role in reducing the standard error of the mean? What are the implications of increasing the sample size? Q2: Why might one be interested in determining a sample size before a study is undertaken? How do population variability and a level of certainty affect the size of
An investment firm with 10,000 clients would like to accurately forecast the average dollar amount their current customer will deposit over the coming year. They decide to telephone a random selection of 25 of their customers to ask how much they plan to deposit, and they would like to keep this sample as small as possible so th
How I would obtain a 150 representative sample size?
In order to be accepted into a top university, applicants must score within the top 5% on the SAT exam. Given that SAT test scores are normally distributed with a mean of 1000 and a standard deviation of 200, what is the lowest possible score a student needs to qualify for acceptance into the university? A) 1330 B) 1400 C
1. The Arkansas State Police wish to estimate the average mph being traveled on the interstate highways, which cross the state. If the estimate is to be within 8 mpg of the true mean with 98% confidence and the estimated standard deviation is 22 mph, how large a sample size must be taken? 2. The odds in favor of an event ar
Sample Size for Weights of Quarters The Tyco Video Game Corporation finds that it is losing income because of slugs used in video games. The machines must be adjusted to accept coins only if they fall within set limits. In order to set these limits, the mean weight of quarters in circulation must be estimated. A sample of qu
Toyota provides an option of a sunroof and side air bag package for its Corolla model. This package costs $1400 ($1159 invoice price). Assume that prior to offering this option package, Toyota wants to determine the percentage of Corolla buyers who would pay $1400 extra for the sunroof and side air bags. How many Corolla buys
Please see the attached file. A company wants to conduct a telephone survey of randomly selected voters to estimate the proportion of voters who favor a particular candidate in a presidential election, to within 2% error with 95% confidence. It is guessed that the proportion is 53%. 1. What is the required minimum sampl
1) In order to set rates, an insurance company is trying to estimate the number of sick days that full time workers at an auto repair shop take each year. A previous study indicated the standard deviation was 2.8 days. How large a sample must be selected if the company wants to be 95% confident that the true mean differs from th
A previous analysis of paper boxes showed that the standard deviation of their lengths is 13 milimeters.
A previous analysis of paper boxes showed that the standard deviation of their lengths is 13 millimeters. A packer wishes to find the 80% confidence interval for the average length of a box. How many boxes does he need to measure to be accurate within 3 millimeters? a.14 b.19 c.51 d.31
A previous study of nickels showed that the standard deviation of the weight of nickels is 250 miligrams.
A previous study of nickels showed that the standard deviation of the weight of nickels is 250 miligrams. A coin counter manufacturer wishes to find the 90% confidence interval for the average weight of a nickel. How many nickels does he need to weigh to be accurate within 15 miligrams? a. 457 b. 278 c. 752 d. 1068
In computing sample size for estimating population proportions, the formula involves p(1-p) (where we don't know p). We use p = ½ if we don't know anything about it, since that is a "worst case". Find the values of p(1-p) for p=.01, .02, .05, .10, .15, .20, .30, .40., .50, .60, .70,.80, .85, .90, .95, .98, and.99. Be prepared t
Why is it important to determine the size of a sample precisely? What are the key points to consider when determining sample size? Frame your answer with business-related examples in mind.
Chapter 6 (Book "Sampling of Populatations" 3rd edition) 1. Ester is an epidemiologist and body builder She is planning a survey of Chicago area body builders to determine the proportion who have ever used anabolic steroids. Her sampling frame consists of membership lists obtained from all accredited health clubs in the six
Select one of these articles and provide an overview of the contents and apply the concepts to the Job Satisfaction survey. It is important to cover the concept of the techniques used to estimate sample size. Simple rules shape proper sample size Section: Special report RESEARCH ? A numbers game How low can you go? No,
The CEO of a company wants to estimate the proportion of Americans who own their house. What sample size should be obtained if he wants the estimate to be within 0.02 with 90% confidence if a. He uses an estimate of 0.675 from the American Census Bureau? b. He does not use any prior estimates?
Business Problem Paper and Optional Presentation a. Clearly define the dependent and independent variables that are the focus of the team's study. The dependent variable is the variable whose value is the result or is a function of the control or independent variables. b. State the null and alternative hypotheses and the
See attached file for full problem description. 16. A study of 305 computer chips found that 244 chips functioned properly. Develop a 99 percent confidence interval for the population proportion of properly functioning computer chips. 17. A correctional institution would like to report the mean amount of money spent per d
You plan to conduct a survey to find what proportion of the workforce has two or more jobs. You decide on the 95 percent confidence level and state that the estimated proportion must be within 2 percent of the population proportion. A pilot survey reveals that 5 of the 50 sampled hold two or more jobs. How many in the workforce
**RELEVANT DEPENDENT AND INDEPENDENT VARIABLES **SAMPLE SIZE DETERMINATION AND SURVEY INSTRUMENTS Please help with the following. Team B's proposal paper: ABC Company, a large grocery retailer located on the east coast, is experiencing a significant reduction in employees furthering their education and earning advanced
Find the appropriate minimum sample size: You want to be 95% confident that the sample variance is within 40% of the population variance. Sample size must be an integer.
What are the elements that affect determination of sample size?
Bea asks Brian the sample size and the timeframe. Brian responds, 140,000 Suppose the bank has one million customers in the USA (where the survey is conducted) With a 95% confidence level and a margin of error of 3%, what would you recommend the minimum sample size to be? This is the minimum sample size. In practi
The Democrat and Chronicle reported that 25% of the flights arriving at the San Diego airport during the first five months of 2001 were late (Democrat and Chronicle, July 23, 2001). Assume the population proportion is p = .25 a. Show the sampling distribution of p, the proportion of late flights in a sample of 1000 flights.
A) A nutritionist wants to estimate the mean amount of cholesterol in a certain variety of chicken eggs. She wants to be within 14 mg. with 99% confidence. It is believed that the standard deviation is 25 mg. How large a sample of eggs should she use? B) A nurseryman wants to estimate how many poinsettias he will need for Ch
Why is it important to determine an appropriate sample size and how can you determine what sample size you should use to ensure that your population mean (mu) is within your confidence interval?
A sample of 12 homes sold last week in St. Paul, Minnesota, is selected. Can we conclude that as the size of the home (reported below in thousands of square feet) increases, the selling price (reported in $ thousands) also increases? Home Size Selling (thousands Price of square feet) ($ thousands)
Problem (also attached): 1) An Entomologist wishes to estimate the average development time of the citrus red mite correct to within .5 day. From previous experiments it is known that standard deviation is in the neighborhood of 4 days. How large a sample should the entomologist take to be 95% confident of her estimate.